Vitreous cement for plugging teeth and process of manufacturing the same.



' King of Prussia, German Emperor, residing at 7.1 Kantstrasse, Charlottenburg, in the UNITED STATES PATENT orrron."

JOSEFV R'AWITZER, or CHARLOTTENBURG, GERMANY.

vnmzous CEMENT FOR PLUGGING TEETH AND PROCESS OF mumcrunme THE SAME.

Specification of Letters Patent.

Patented Sept. 18, 1906.

Application filed February 12. 1906. Serial No. 300,737.

To all whom, it may concern: Be it known that I, J OSEF RAwrTzER, doctor of philosophy, chemist, a subject of the Kingdom of Prussia, German Empire, have invented a new and useful Vitreous Cement for Plugging Teeth and Processes of Manufacturing the Same, of which the following is a specification. 7

My invention relates to the manufacture of a material which on being triturated with phosphoric-acid salts of the same hardens to orm a vitreous cement which is adapted to be used for plugging teeth, for cementing porcelain, and the like.

Hitherto zinc phosphate cements have been almost exclusively used as mineral tooth-plugging materials-that is to say,

mixtures com osed 'of highly-burnt oxid of zinc with ad itions'of oxide of the earthalkaline metals, aluminium, and of silicic acid, &c. These masses are not advantageous because they are not transparent and may be easily dissolved by the acids of the mouth, thus becoming observable in the teeth-in an objectionable manner. It has been proposed, however, to prepare transparent tooth-cements, and silicate of aluminium has been used chiefly for the purpose that is, e. 9., one part of lime, three parts of silicic acid, and six arts of oxid of aluminium have been melted together and the mass after cooling mixed With a solution. of phosphate of tin in phosphoric acid; but even this mass is too soluble in the acids of the mouth, has not sufficient hardness, and shrinks in the teeth, for which reasons the mass has been found impractical. Later the solubility of 'such tooth-cements was diminished by adding silicate of beryllium to a molten silicate of lime and aluminium. This mass was, however, too brittle, so that it could not be used for making outlines. It was also found to shrink in such a high degree that asecondary caries could not be avoided and the mass could not be used in the phantom and in the teeth out of the mouth.-

I have found that a tooth-cement can be made equivalent. -to the beryllium silicate masses with reference to insolubility, hardness, and transparency, but superior to the beryllium silicate masses with referenceto brittleness and shrinklng by adding aluminium silicate repared in a wet way to molten silicate of ime and aluminium, and that aluminiumsilicate apt for manufacturing a tooth-cement can be prepared by adding a solution of an organic or inorganic aluminium salt to a solutionof an alkali silicate mixed with the amount of an hydroxid of alkali required for neutralizing the amount of acidpresent in the aluminium salt. An aluminium present invention I mix, for instance, four to six parts of the said finely-ground aluminium silicate with eight partsof a molten, cooled, finely-ground mixture of one part of oxid of calcium, two parts of silicon anhydrid, and one part of oxid ofaluminium. In using the mixture for filling teeth I mix the mass with a solution of phosphoric acid of specific gravity 1.5 containing one hundred and fifty grams of A1 0 in one'liter. The skilled workman will find by experiment the amount of the phosphoric acid suitable for his special purpose. The proportions can be varied, es ecially the amount of silicic acid in the mo ten mass. The calcium oxid may be replaced b magnesia. I

Instead oft e phosphoric acid for triturating the mixture of the silicates I canalso use acid salts of the phosphoric acidfor instance, the acid potassium 'phosphate or similarcompounds of the other light metals, including zinc, if required, with addition of coloring-matters. Compounds of the beforementioned kind are the oxide, basic phosphates,-borates, and silicates, also fiuorids of each of the before-mentioned metals alone or corresponding double salts of several of them.

What I claim as my invention, and desire to secure by Letters Patent, is

1. The process of manufacturing a material designed for the production of cement, consistingin preparing in a wet way aluminiumv silicate Al,O SiO,, drying the same so that it contains no more than six per cent. oxid of calcium, oxid of aluminium and of to of Water, mixing the said dried aluminium silicon anhydrid.

silicate with a finely-ground material pro- In testimony whereof I have signed my duced by melting lime, aluminium oxid and name to this specification in the presence of silicon anhydrid together. two subscribing witnesses.

2. As a new article of manufacture a ce- JOSEF. RAWITZER. ment composed of a mixture of aluminium Witnesses? silicate containing not more than six per HENRY HASPER,

cent. of water, and of a fused mixture of WoLDEMAR HAUPT. 

